Navigational apparatus



Nov., 15, 1949 J. H. BOLLMAN ETAL NAVIGATIONAL APPARATUS 3 Sheets-Sheet 1 Filed Aug. l, 1945 kmrx.

. Jl'l. BULLMAN IN VENTORS F.' A. BROOKS J G.KRE`R JR.

72 a TTORN Nov. 15, 1949 J. H. BoLLMAN ETAL 2,488,371

NAVIGATIONAL APPARATUS Filed Aug. l, 1945 3 Sheets-Sheet 2 RErnAc:

PULSE AMP ofrLfcr.

co/Ls :weep

c/ ncu/ r BEA RING Patented Nov. 15, 1.949

NAVIGATIONAL APPARATUS John H. Bollman, Rutherford, Fred A. Brooks, Maplewood, and John G. Kreer, `I r., Bloomiield, N. J., assignors to Bell Telephone Laboratories. Incorporated, New York, N. Y., a, corporation of New York Application August 1, '1945, Serial No. 608,286,

Claims.

This invention relates to an echo ranging system, and particularly to an arrangement for producing a plurality of navigational readings on a, single indicator in such system.

In the use of underwater echo ranging systems at sea, certain navigational readings such, for example, as the bearing of the sound projector relative to true north, range of the target, training of the sound projector relative to the target, and course of the ship relative to true north, are essential in order to promote the most efficient use of the system. Heretofore, these readings having been obtained by mechanisms designed to operate two or more individual indicators.

The main object of the invention is to produce expeditiously on a single indicator la plurality of essential navigational readings used in an underwater echo ranging system.

In an underwater echo ranging system described hereinafter and constituting a specific embodiment of the invention, there are combined a cathode-ray oscilloscope including deiiecting coils a sound projector, a potentiometer having two brushes xedly disposed at 90 degrees relative to each other for supplying two voltages to the deflecting coils, and a shaft connected to these brushes and rotated in response to changes in the ships course. Such rotation of the shaft effects a proportional angular change in the positions of the two brushes in the potentiometer whereby the voltages supplied to the deecting coils are varied as the sine and cosine of the angle of rotation of the shaft. This in conjunction with other features of the system produces expeditiously on the CRO screen respective indications of (a) course of the ship relative to true north, (b) range of the target, (c) training of the sound projector relative to the target, that is, whether such projector is trained directly on the target, or to the right or left thereof, and (d) bearing of the sound projector relative to true north.

The invention will be readily understood from the following description taken together with the accompanying drawing in which:

Figs. 1 and 2 are a schematic illustration of an underwater echo ranging system including a specific embodiment of the invention,

Fig. 3 is anindicaton of several navigational readings produced on a single indicator in accordance with Figs. 1 and 2. and

Fig. 4 is a schematic circuit illustrating the connections of the sweep circuit and retrace pulse amplifier shown in box form in Fig. 2.

Figs. 1 and 2 show an underwater echo ranging system for ascertaining both the distance to and the right or left direction of a target, with reference to a ship on which such system is located. Rererring to rigs. 1 and 2, the system comprises -a keying apparatus I0 for controlling the energization and deenergization of an electromagnetic relay Il whereby transmitting apparatus I2 and receiving apparatus I3 are alternatively connected via conductor pairs I and 8 to a sound projector or transceiver I4 embodying right and left halves R and L, respectively, and having aunidirectional action that will be mentioned later. The output of receiving apparatus I3 is connected over conductor path 9 to the input of a bearing deviation indicator I6 ywhose output is connected to denecting coils I'I and I8 of cathode-ray oscilloscope CRO having a luminescent screen. The bearing deviation indicator I6, as will be hereinafter pointed out, produces on the CRO screen visual indications of the range of the target and of the training of the unidirectional action of the transceiver I4 whether to the right or left of the target or on the target. Thus, the bearing deviation indicator I6 shows essentially the right or left d'i'rection of the target relative to unidirectional action of the transceiver Il.

In the operation of the circuit portion described so far, the keying apparatus IU normally connects transceiver I4 to receiving apparatus I3 via the respective back contacts of relay H which is deenergized, as shown in Fig. 2. When the keying apparatus I0 is operated to energize relay II, the transmitting apparatus I2 supplies an electrical pulse having a frequency say, of the order of 24 kilocycles per second, to both halves R and L of the transceiver I4, via the front contacts of rel-ay II. The transceiver I4 translates such electrical pulse into a sound pulse and imparts the latter into the surrounding water in a unidirectional beam. Immediately thereafter the keying apparatus I0 deenergizes relay II to disconnect the transmitting apparatus I2 from the transceiver I4 and to reconnect the receiving apparatus I3 thereto.

When the sound pulse strikes a distant object or target in the water, a portion of the sound pulse is reflected therefrom as an echo and is ultimately picked up by the transceiver I4 and thereby translated into an electrical pulse. The latter pulse is supplied to the bearing deviation indicator I6 for a purpose that will be presently explained. When the relay II was operated to the transmitting condition as just explained, its lowermost lower front contact served to apply direct current from source 20 to sweep circuit I9. This causs a sweep voltage to be applied to deecting coils 2l and 22 via leads 43a. 44a and thereby to start a cathode-ray trace extending in a radial direction on the CRO screen. Depending on the training of the unidirectional beam of the transceiver I4 relative to the target, the bearing deviation indicator I6 causes the trace to assume a configuration characterized as follows. When the unidirectional beam of the transceiver I4 is trained directly on the target, no appreciable change is made in the configuration of the cathode-ray trace except a bright spot is produced therein as explained subsequently. As the unidirectional beam of the transceiver I4 is trained to the right or left of the target, the cathode-ray trace is caused to move sharply to the right or left, respectively, whereby a "pip" is introduced into the configuration of the trace. Since the CRO screen is calibrated in yards along a radial line, the location of the pip in the trace along such line will indicate directly the distance to the target. The position of the pip on the right or left side of the trace will indicate the transceiver is trained to the right or left, respectively. of the target. For each actuation of the keying apparatus I as 'above explained, the sweep circuit I9 goes through one cycle of its operation. For further details regarding the system described thus far, reference is made to the copending application of J. H. Bollman Serial No. 520,875, filed February 3, 1944, and to the copending application of J. G. Kreer, Jr., Serial No. 561,448, filed November 1, 1944.

'Ihe transceiver I4 is rotated in azimuth by a mechanism `actuated by a han'dwheel 25 or by the ships gyro-compass system 26. Handwheel is mechanically connected via differential gear linkage 24, shaft 25a, gear box 21 to shaft 28 carrying rotor '29 of synchrocontrol transformer 30. Differential gear linkage 24 is :also mechanically connected through shaft 43, bevel gears 44 and shaft 45 to gear box 46. Stator 33 of synchrocontrol transformer is connected to stator 34 of transmitting synchro generator which includes a rotor 36. This rotor is electrically connected to the ships gym-compass system 26 energized from a source 31 of alternating current power, and is also mounted on a shaft 36a rotated by the ships gyro-compass system 26 in the familiar manner.

Rotor 29 is connected through transformer 38 to the input circuits of gas-filled tubes 39, 40, 4I and 42 Whose anode circuits are connected by transformers 41 and 48 to the alternating power source 31 and by transformer 49 to Winding 50 of spinner motor 3 I. This motor is mechanically connected by shaft 31a, gear box 46 and shaft 5I to brushes 4Ia movably positioned on secondary winding 52 of a commutator transmitter 32 whose primary winding 53 is energized from the alternating rpower source 31; and also via gear box 46 to the rotor 29 through the mechanical connection previously traced. The secondary winding 52 is connected via brushes 4Ia to the delta-connected winding of training motor 54 having a single-phase winding connected to the alternating power source 31. A shaft 55, gear box 56 and shaft 51 connect the training motor 54 to the transceiver I4. Gear box 56 also includes a shaft 15 on one end of which is positioned rotor 16 of a transmitting Selsyn motor 11 having a threephase stator 18. This stator is connected directly to three-phase stator 19 of a receiving Selsyn motor 89 whose rotor 8l is mounted on one end of a -shaft 59 that has itsopposite end connected to gear box 60. A shaft 13 has one end connected :to gear box 60 and its opposite end to differential gear linkage 1I. The rotors 16 and 8l are electrically connected in parallel to the alternating power source 31.

Inv the operation of the foregoing mechanism `ttor rotating the transceiver I4 in azimuth either actuation of handwl'ieel 25, effecting rotation of shaft 23 and rotor 29 thereon, or operation of the ships gym-compass system 26, causing rotation of shaft 36a and rotor 36 thereon, establishes electrical unbalance in the transformer 30 whereby a voltage of certain magnitude and sign is applied through transformer 38 to the input circuits of gas-filled tubes 39, 40, 4I and 42. This voltage, depending on its sign, causes either tubes 39 and 42 or 40 and 4I to fire when such voltage is in phase with the voltage in the anode circuits of the respective tubes whereby a voltage of certain sign and magnitude is applied from the alternating power source 31 through transformer 49 to the win-ding 50 of spinner motor 3I. As a consequence, spinner motor 3| is caused to rotate in either a clockwise or counter-clockwise direction, depending on the sign and magnitude of its energizing voltage, to repeat the corresponding rotation of handwheel 25 or change in the ships compass embodied in the ships gyro system 26. Rotation of spinner motor 3| imparts rotary movement to shaft 3Ia, gears in gear box 46 and shaft 5I and thereby to the brushes 4Ia on the winding 52. The positioning of the brushes 4la relative to the midturn of secondary winding 52 of the commutator transmitter 32 determines the magnitude and phase of a three-phase voltage supplied to the delta-connected winding of training motor 54. The interaction of the magnetic elds due to the voltage effective in the delta-connected and single-phase windings of training motor 54 lproduces a torque whose direction and magnitude depend on the relative magnitudes and phase of the voltages of the respective windings. This torque effects rotation of shaft 55, gears in gear box 55, and shaft 51 and thereby rotation of the transceiver I4 in azimuth in either clockwise or counter-clockwise directions, depending on the direction of rotation of handwheel 25 or change in the ships course/as above mentioned. An Rf-C network 43h connected to cathodes of the gasfilied tubes 39, 49, 4I and 42 -ai-ds in rotating the transceiver I4 to its final position without hunting or overshooting. For further details concerning the foregoing mechanism for rotating the transceiver I4 in azimuth reference is made to the copending application of J. H. Bollman, Serial No. 585,319, led March 28, 1945, now Patent No. 2,478,740, issued August 9, 1949. The differential action of the differential gear linkage 24 i-s so arranged that, in response to actuation by handwheel 25, rotary movement is i-mparted to the shaft 25a and the gears and shafts associated therewith to establish electrical unbalance in the transformer 30 as above explained but no rotary movement is imparted to .the shaft 43 and the gears Iand shafts connected thereto. However, the differential action of the differential gear linkage 24 is further arranged that, in response to fthe rotation of the gears in gear box 46 by motor 3l, this rotary movement is imparted to shaft 45, gears 44, shaft 43 and gears in differential gear linkage 24, shaft 25a. gears in gear` 5 25 or change in the ships course. When electrical unbalance is established in the synchrocontrol transformer 36 Iby an initially predetermined rotation of the shaft 25a in response to actuation of the handwheel 25 for causing a predetermined rotation of the transceiver I4 in azimuth, electrical balance is restored to the synchrocontrol transformer 30 by an equivalent rotation of the shaft 25a in the opposite direction under control of the motor 3| as above mentioned. Thus,

the handwheel 25 serves Vto rotate the transceiver I4 in azimuth with no net rotation of the shaft 25a.

When, however, electrical unbalance is established in .the synchrocontrol transformer 30 under control of the ships gyro system.y 26 in response Vto changes in the ships course, the ships gyro system 26 initially rotates the shaft 36a associated therewith and carrying rotor 36 of synchrogenerator 35 but does not directly affect the position of vthe shaft 25a or that of the rotor 29 of synchrocontrol transformer 30. Rotation of the rotor 36 of synchrogenerator 35 varies the magnitude of Ithe voltage induced in the winding 34 of synchrogenerator 35 and supplied thereby to the winding 33 of synchrocontrol transformer 30 whereby electrical unbalance is introduced therein. As previously explained, this unbalance energizes the motor 3| which produces the rotation of transceiver I4 in azimuth and .the initial rotation of shaft 25a to an amount depending on the magnitude of the change in the ships course. This initial rotation of the shaft 25a serves, as previously explained, to cause rotation of the rotor 29 of the synchrocontrol transformer 30 until electrical balance is restored thereto. This initial rotation rernains in the shaft 25a until the ship again changes its course. Thus, .the ships gyro system 26 serves to rotate the transceiver I4 in azimuth with net rotation of the shaft 25a. Inasmuch as the shaft 25a is rotated under the control of the ships gyro-compass system 26 in response to changes in the ships course, the rotational position of the shaft 25a gives the ships course relative to .true north.

Referring again to Figs. 1 and 2, gear box 21 is connected via shaft 10, differential gear linkage 1 I and shaft 12 to a frame 14 carrying the deflecting coils I1, I8, 2| and 22 in xed relation and insulated therefrom. As the transceiver I4 is rotated in azimuth in the manner hereinbefore mentioned, frame 14 and the deecting coils I1, I3, 2| and 22 thereon are rotated in clockwise or counter-clockwise direction about the cathoderay in the oscilloscope. Instead of the cathoderay trace rising only along a single radial direction, this trace may also extend in radial direction through 360 degrees from the center of the CRO screen. Hence, the CRO screen may be calibrated with a plurality of circles concentrically positioned with reference to the center thereof and equally spaced to indicate the target range from to 1,000 yards. An outermost circle 100 disassociated from the range circles is calibrated in 360 degrees. Multiplying factors of 2, 3, 5 and may be embodied in the sweep circuit I9 in the well-known manner to provide effective ranges of 2,000, 3,000, 5,000 and 10,000 yards, respectively. Other multiplying factors may be utilized to provide other ranges.

The portion of system of Figs. 1 and 2 above described, is so arranged that when the transceiver I4 has its unidirectional beam trained directly on true north and the bow of the ship along the fore-aft line thereof, the deecting coils I1, I6, 2| and 22 are positioned as shown in Fig. 2. Accordingly, thesweep circuit I9 and deflecting coils 2| and 22 will cause the cathoderay trace to rise vertically upwardly toward true north on the CRO screen. and the bearing deviation indicator I6 and deilecting coils I1 and I8 will vary the configuration of the cathode-ray trace to indicate the range, and the right-left training of the transceiver I4, as hereinbefore explained.

When the unidirectional beam of the transceiver I4 is trained directly on true east, the deilecting coils I1, I8, 2| and 22 will be displayed 90 degrees in a clockwise direction relative to their positions in Fig. 2. As a consequence, the sweep circuit I8 and defiecting coils 2| and 22 will cause the cathode-ray trace to extend horizontally to the right toward true east. Assuming the unidirectional beam of the transceiver I4 to be trained directly on the target, the received echo will so operate the bearing deviation indicator I6 and thereby the deecting coils I1 and I8 as to cause no appreciable change in the configuration of the horizontal cathoderay trace. Should, however, the unidirectional beam of the transceiver I4 be trained to the right or left of the target, then the received echo will so operate the bearing deviation indicator I6 and thereby the deflecting coils I1 and I8 as to cause a pip to occur below or above, respectively, the horizontal cathode-ray trace.

When the unidirectional beam of the transceiver I4 is trained directly on true south, or the stern of the ship, along the fore-aft line thereof, the deflecting coils I1, I8, 2| and 22 will be displaced 180 degrees relative to their. positions in Fig. 2. The action of the cathode-ray trace and pips described above regarding true north will be repeated except now the cathode-ray trace will extend vertically downwardly toward true south, and the pips will provide opposite indications as to the right or left direction of the target. When the unidirectional beam of the transceiver I4 is trained directly on true west, the `deflecting coils I1, I8, 2| and 22 will be displaced degrees in a counter clockwise direction relative to their positions in Fig. 2. The action of the cathode-ray trace and pips explained previously concerning true east will be repeated except now the cathode-ray trace will extend horizontally to the left toward true west and the pips will provide opposite indications as to th'e right or left direction of the target.

Let it be assumed the transceiver I4 has been trained by handwheel 25 as described hereinbefore to a bearing of 020 degrees relative to true north. This means that the motor 3| has been energized to rotate the transceiver I4 the desired amount, and has been deenergized thereafter, as hereinbefore described. Also, this means rotary movement has been imparted to the gears of` differential gear linkage 24, shaft 25a, gears in gear box 21, shaft 10 and gears of differential gear linkage 1I. This movement tends to rotate the shaft 12 and thereby the frame 14 carrying the deecting coils I1, I8, 2| and 22 in a clockwise direction, but due to the differential action of gear linkage 1| fails to disturb the shaft 13. Since in response to actuation of the handwheel 25, the transceiver I4 is rotated in azimuth with no net rotation of the shaft 25a as above described, it is obvious in this case that the shaft 25a causes no net rotation of the shafts 10 and 12, and of frame 14. At the same time, however, the gears in gear box 56 eiect rotation of the shaft 15 and the rotor 16 carried thereby. This changes the phase and magnitude of the three-phase voltage induced in the stator 18 and supplied to the stator 19. As a consequence, the interaction of the magnetic fields occasioned by vthe alternating voltages eiective in the associated stator 19 and rotor 8| produces a torque whose magnitude and direction depend on the relative phase and magnitude of the alternating voltages effective in the respective rotor and stator. This torque effects corresponding rotation of the shaft 59, gears in gear box 60, shaft 13 and gears in differential gear linkage 1|.

Due to the differential action of the dilerential gear linkage 1I, the rotation of shaft 13 does not disturb the rotational position of shaft but does tend to affect the rotational position of the shaft 12 in a manner that will now be explained. The rotational position of the shaft 13 follows the training of the unidirectional beam of the transceiver I4 relative to the bow of the ship, and, therefore, the shaft 13 gives the direction of such training of the transceiver |4. In response to the rotation of shaft 10 as abovementioned, the gears in differential gear linkage 1| tend to rotate the shaft 12 in one rotary direction, but in response to the rotation of shaft 13 tend to rotate the shaft 12 in the opposite rotary direction. Thus the effective amount of rotation of the shaft 12 comprises the difference between the rotary movements of the shafts 10 and 13.

As the rotational position of the shaft 25a, and

therefore the corresponding position of the shaft 19, gives the ships course relative to true north,

and as the rotational position of the shaft 'I3 gives the training of the unidirectional beam of the transceiver I4 relative to the bow of the ship, then the rotational position of the shaft 12, which 'is the difference between the rotational positions of the shafts 1|! and 13, gives the direction of training of the unidirectional beam of the transceiver I4 relative to true north. Accordingly, the shaft 12 rotates the frame 14 and thereby the deecting coils I1, I8, 2| and 22 about the cathode-ray so as to deflect the cathode-ray in such manner that the trace produced on the oscilloscope screen indicates the training of the unidirectional beam of the transceiver I4 relative to true north. This will now be described, and as previously assumed, will be 020 degrees relative to true north.

The transmitting apparatus I2 is now operated to energize transceiver I4 whereby a sound pulse is imparted into the surrounding water, and subsequent thereto the receiving apparatus I3 is conditioned to receive the echo from the target as hereinbefore explained. At the instant of the transmission of the sound pulse, an impulse of direct current from the source is supplied to the sweep circuit I9 which cnergizes the deflecting coils 2| and 22. As a consequence, the cathode-ray trace 95 of substantially smooth contour is caused to extend in an oblique and upward direction to the right from the center of the CRO screen as shown in Fig. 3. In due course, the echo is picked up by the transceiver I4, supplied to the receiving apparatus I3, and thereafter passed along to the bearing deviation indicator |6. This indicator energizes the deecting coils I1 and I8 which thereupon produce, for example, the relatively bright spot 96 which indicates a range of 400 yards to the target and the transceiver I4 is directly trained on the target.

Instead of the spot 96,!1et it be assumed the echo eventually caused, as a second example, pip 91 in the cathode-ray trace 95. This would indicate a range of 600 yards and the direction of the target was to the left of the transceiver I4. .Rotating transceiver I4 in a counter-clockwise direction would eventually train it on the target to duplicate the spot 96 at 600 yards. Instead of either spot 96 or pip 91, let it be assumed the echo effects, as a third example, pip 98 in the cathode-ray trace 95. This would indicate a range of 800 yards and the direction of the target was to the right of transceiver I4. Rotating transceiver I4 in a clockwise direction by the handwheel would subsequently train the former on the target to duplicate the bright spot 96 at 800V yards. Continuation of the cathode-ray trace 95 substantially to the point 99 would indicate the bearing of the unidirectional beam of the transceiver I4 to be approximately 020 degrees relative to true north, as previously assumed. In the absence of an echo, the cathode-ray trace would extend substantially smoothly to the point 99 to indicate only such bearing of transceiver I4 relative to true north.

Similar action may be traced in the above described circuit when unbalance is introduced in the transformer in response to changes in the ships course. In this case, however, the training of the unidirectional beam of the transceiver I4 is adjusted relative to the bow of the ship but is unchanged relative to true north.

Thus, the portion of the system of Figs. 1 and 2 hereinbefore explained produces simultaneously on the CRO screen indications of (a) the range of the target, (b) the training of the unidirectional beam of transceiver I4 relative to the target, that is, whether this beam is disposed directly on the target, or to the right or left thereof, and (c) the bearing of the unidirectional beam of transceiver I4 relative to true north.

In accordance with important features of the present invention there is produced on the same CRO screen an indication of the bearing of the ship relative to true north.

Referring to Figs. 1 and 2, shaft 82 has its upper end connected to gear box and its lower end joined to a rotatable frame 83 in which is mounted arms or brushes 84 and 85 suitably insulated therefrom and xedly located at 90 degrees with reference to each other for slidable movement on resistor 86a, the arms and resistor constituting a potentiometer 86.

Brush 84 is connected by lead 81 to deflecting coil I8, and brush 85 by lead 88 to lead 44a and thereby to deflecting coil 2|. Diametrically opposite points 89 and 90'on the resistor 86a are connected by leads 9| and 92, respectively, to the output of retrace pulse amplifier 93 whose input is connected to sweep circuit|9 and whose operation will be explained later. Lead 94 also connects the output of retrace pulse amplifier 93 to lead 43a and thereby to deecting coils 2| and 22. The circuit connections of the sweep circuit I9 and retrace pulse amplifier 93 shown in Fig. 4 are conventional, and are illustrated, for example, on data sheet 2, December 15, 1944, of the Radio Corporation of America tube handbook. In the circuit of Fig. 4, the condenser C9 is so proportioned as to pass the rapidly varying or decreasing portion of the saw-tooth sweep voltage but to block the slowly varying or 1ncreasing portion of the saw-tooth sweep voltage. Thus, the amplied retrace or decreasing portion of the saw-tooth wave of the sweep circuit I 9 is divided into two portions and applied to the deilecting coils I'l, I8, 2| and 22 as follows: One portion in a circuit comprising common lead 94 and lead 92, terminal 90, resistor 86a, arm 85 and lead 88; and a second portion in a circuit including common lead 94 and lead 9I, terminal 89, resistor 86a, arm 84, lead 81 and lead |05.

The operation of the specific embodiment of the invention is as follows:

At the time the torque due to the interaction of the magnetic fields of stator 'I9 and rotor 8I of motor 8II caused rotation of shaft 59, gears of gear box 6|) and thereby shaft 13, it also caused the gears of gear box 60 to effect rotation of shaft 82 in a predetermined direction through a certain angle, say, for example, angle c. This angle is the direction angle between the fore-aft line of the ship and the unidirectional beam of transceiver I4. The angular movement er causes the brushes 84 and 85`to move a proportional angular distance in a corresponding direction on the resistor 86a. As a consequence, the two voltages applied to the deecting coils I1, I8, 2I and 22 in the circuits previously traced are varied .in accordance with changes in the angle o' to produce on the CRO screen a spot 69 in a manner that will now be explained.

The retrace pulse amplifier 93, Fig. 2, has a frequency characteristic for selecting the high frequency component of the decreasing portion of the saw-tooth wave produced in the sweep circuit I9 as above mentioned with reference to Fig. 4. For the purpose of this explanation, the

component so amplified may be designated voltage E which is divided into two portions and applied to the deflecting coils II, I8, 2| and 22 in the circuits previously traced. As the brushes 84 and 85 are actuated through 360 degrees in either a clockwise or a counter-clockwise direction on the resistor 86a, the eiective voltages on the respective brushes will vary from a maximum of one sign, through zero, to the maximum of the opposite sign. Due to the mechanical spacing of 90 degrees between the brushes 84 and 85, the effective voltages on the respective brushes will be displaced 90 degrees. Thus. a voltage E sin a is effective between common lead 94 and brush 85; and a voltage E cos u is effective between common lead 94 and brush 84. These voltages are applied to the respective deecting coils I 'I, IB, 2I and 22 by means of the circuits above traced. As a consequence, the cathoderay spot 69, Fig. 3, is displaced on the CRO screen a distance E sin a along the axis of coils I'I and I8, and a distance E cos a perpendicular to the axis of coils I 'I and I8. This results in a deilection of the spot 69 from the axis of the coils I'I and I8 at an angle b which is proportional to the angle a. Since the coils I 'I and I8 are Vrotated a certain angle by the shaft 'I2 to give the bearing of the unidirectional beam of transceiver I4 relative to true north, as above mentioned, and the angle a is the angle of the unidirective beam of the transceiver I4 relative to the foreaft line of the ship as above pointed out, the angular position of the spot 69 on the CRO screen will indicate the difference between these angles, or the bearing of the ship relative to true north. This indication is therefore produced on the single CRO screen together with the other indications previously identified and eiiected by other features of the system.

What is claimed is:

1. In combination with a system for navigating a steerable vehicle relative to a target, comprisl0 Y ing on said vehicle a transceiver for imparting a sound pulse into a surrounding medium and receiving an echo from said target located therein, compass-controlled means for obtaining the bearing of said vehicle relative to true north, manual means for training said transceiver relative to a fore-aft line of said vehicle, an oscilloscope having a screen and beam deflecting coils, and means repsonsive to said echo and to the angular difference between the vehicles bearing relative to true north and the transceivers training relative to said vehicle for energizing said coils to produce simultaneously on said screenindications of the range of said target, the training of said transceiver relativel to said target, and the bearing of said transceiver relative to true north, means for supplying to said coils two voltages varying as the sine and cosine of the angle of training of said transceiver relative to the fore-aft line of vsaid vehicle to produce on said screen an indication of the bearing of said vehicle relative to true north.

2. A combination according to claim 1 in winch said voltage supplying means comprises a shaft rotated an angular amount that is proportional to the angular training of said transceiver relative to the fore-aft line of said vehicle, and means controlled by said shaft for supplying to said coils said two voltages varying as the sine andr cosine of said angular amount, said last means producing on said screen said indication of the vehicles bearing relative to true north and displacing said last indication from the indication of the transceivers bearing relative to true north a further angular amount that Vis proportional to said angular amount.

3. A combination according to claim 1 in which said voltage supplying means comprises a potentiometer having a pair of brushes iixedly disposed at 90 degrees relative to each other, a

source of voltage, means for connecting said source, potentiometer-and brushes in circuit to supply the two voltages to said coils. and a shaft actuating said brushes an angular amount that is proportional to the angular training of said transceiver relative to the fore-aft line of said vehicle, said brushes varying said two voltages as the sine and cosine of said angular amount, said two voltages energizing said coils for producing on said screen said indication of the vehicles bearing relative to true north and displacing said last indication from the indication of the transceivers bearing relative to true north a further angular amount that is proportional to said angular amount.

4. In combination with a dirigible vehicle, a navigational instrument on said vehicle comprising a cathode-ray oscilloscope having a pair of deilectors adapted to deflect the cathode-ray in mutually perpendicular directions, said pair being mounted for rotation about said ray, a transceiver for transmitting a pulse of energy in a unidirectional beam from said vehicle and receiving an echo resulting from the reflection of said energy from a distant object, compass-controlled means to actuate said transceiver for maintaining said beam xed in position relative to true north irrespective of changes in the course of said vehicle, means independent of said last means for manually adjusting the position of said transceiver and thereby said beam with reference to a fore-aft line of said vehicle, means differentially responsive to said compass-controlled means and said manually adjusting means for controlling the rotational position of said pair of deflectors, control means having an angular displacement that is proportional to the angular displacement of said beam with reference to the fore-aft line of said vehicle, means for applying respective operating voltages to said pair of deiiectors, and means including said control means for varying said operating voltages as the sine and cosine of said angular displacement of said control means.

5. In an echo ranging system, an object detector comprising an energy beam transceiver adapted to operate with directionally selective effect from a dirigible vehicle, means independent of variations in the heading of said vehicle for varying the direction in which said transceiver is operative with reference to the front end of said vehicle, a cathode-ray oscilloscope including a luminescent screen and a relatively rotatable pair of ray deector means adapted to deiect the cathode-ray in mutually perpendicular directions across said screen in response to applied deflecting voltage, means operative on said deector means for repeatedly deecting said ray across said screen in a predetermined direction xed relative to the rotational position of said deector means, means varying the relative rotational position of said deflector means in response to and in conformity with variations in the direction of said vehicles heading relative to true north and in the direction of the opera- 30 tion of said transceiver with reference to a foreaft line of said vehicle whereby the position of the trace made by said defiector means as aforesaid directly indicates said direction of opera- V.tion of -said transceiver relative to true north,

JOHN H. BOLLMAN. FRED A. BROOKS. JOHN G. KREER, JR.

REFERENCES CITES The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,973,673 Rice Sept. 11, 1934 2,296,032 Hammond Sept. 15, 1942 FOREIGN PATENTS Number Country Date 497,147 Great Britain Dec. 9, 1938 546,202 Great Britain July 2, 1942 

